(2014) Mark abstract This PhD thesis contributes to a better understanding of the chemistry of mustard and rapeseed oils in the field of authenticity, formation of antioxidants during roasting and their effects on the oil oxidative stability. At first, a chemometric methodology based on Monte Carlo simulation was developed to evaluate the authenticity of mustard and rapeseed oils. In the second part, the isolation of a potent radical scavenger, canolol, from the roasted mustard seed oil was carried out and its identity was confirmed via spectrometric data (NMR, UV, MS) and chemical synthesis. Canolol was found to be formed during seed roasting by decarboxylation of sinapic acid. In the third part, the oxidative stability of roasted and unroasted mustard seed oils collected from the Nepalese market was evaluated. Furthermore, the effects of seed roasting on the oxidative stability of mustard and rapeseed oils was investigated. These studies showed that canolol could play an important role in the oxidative stability of roasted rapeseed oil; in contrast, it could only play a limited role in the much higher oxidative stability of roasted mustard seed oil. In fact, the oxidative stability of roasted mustard seed oil was mainly correlated with the phospholipid content and the Maillard type browning reaction products formed during roasting. At last, the Maillard type reactions involving phospholipids and their antioxidant potential were evaluated in a model system containing phosphatidylethanolamine and glucose. The reaction products not only increased the oil oxidative stability but also increased the stability of tocopherol and plastochromanol-8 during oil storage. The occurrence of such reactions in an apolar medium was demonstrated by identifying some of the reaction products by liquid chromatography-time of flight mass spectrometry (LC-TOF MS). Such antioxidants could find a wide application in different food products.

Please use this url to cite or link to this publication: http://hdl.handle.net/1854/LU-4283460